Arc chute



J. SLEPIAN July 1o, 1934.

ARG CHUTE Filed Jan. 10, 1929 lNVENTOR .Josep/2 We/afa n.

A T'oRN Y UNITEDSTATES PATENT OFFICE ARC CHUTE Joseph Slepian,Pittsburgh, Pa., assignor to Westinghouse Electric & ManufacturingCompany, a corporation of Pennsylvania Application January 10, 1929,Serial No. 331,469

8 Claims. (Cl. 20o-144) My invention relates to circuit interrupters andMy invention comprises, in general, an insu- Dartieuiariy to circuitinterrupters of the air lating base 1, upon which is mounted astationbreak type wherein Vthe arc incident to the separy contact member2, a magnetic core 3 and aratien f the Contacts iS led into a Space OC-a bracket 4 that supports the movable elements 5 cupied by a pluralityof metal plates or grids of the breaker 5. The foregoing elements may 60and is brokenup into a series of arcs that are be of any type well knownin the art to be suitlapidly deionized and extinguished as they moveable, their precise structure not being claimed between the grids.herein.

As a particular feature 0f my invention here The magnetic core 3 has awinding 6 mounted l0 described, an arc, consequent upon the openingthereon that may be energized, through leads 7, 65 of the circuit, movesinto an arc-extinguishing from any desired control circuit. A movablemeans adapted to divide it into a plurality of contact member 5 iscarried by a pivoted arm 8 short arcs between grids of such form thatamaghaving an armature 9 to be attracted by the netic flux is induced bycurrent flow in the grids magnetic core 3 vwhen the coil 6 is energized.

l5 themselves which moves the arc rapidly over the The arm 8 issupported upon a pivot 11 and has 70 grid surfaces. a lateral extension12 that is attached, by means The rapid movement of the arc within theexof a spring 13, to a stationary bracket 14. tinguishingmeans preventsthe burning and va- Line current is conducted to the extension 12porizin'g of metal which occurs if arc terminals from a terminal bolt 15through a flexible conmove slowly or stand still for any appreciable'ductor 16. The contact member 2 is fastened to 75 time. the base 1 byvolts 17, to one of which is attached I have found that, in circuitbreakers of the the terminal piece of a conductor 18. A similar priorart, vaporized metal combines chemically terminal piece for a conductor18a is attached to with the oxygen of the air for a considerable timethe bolt 15. after the electric arc proper is extinguished; and The modeof operation in moving the mecha- 80 that the ionized products of thiscombustion are nism just described to open-circuit position from afrequent cause of restriking or re-ignition of the closed position shownin Fig. 1 is as follows. the arc. By preventing the formation of suchAssuming the contact member 5 and the memvapors, re-ignition of the arcis prevented. ber 2 to be in engagement, as shown n Fig. l,

In the particular embodiment here shown, the a circuit is completed,through the conductor S5 deionizing means comprises an aggregate of 18,bolt 1'7, contact member 2, contact member spaced plates of U-shape, theadjacent surfaces 5, arm 8, conductor 16 and bolt 15, to the otherbetween the spaced plates being traversed by the conductor 18. terminiof the short arcs into which the original When the coil 6 is(le-energized, the spring 13 arc is broken. The flow of current from theactuates the arm 8 in a contra-clockwise direc- 90 onef to the otherbranch of each U-shaped plate tion, thereby moving the contact member 5away Asets up a magnetic field which causes the short from the member 2,thus producing an arc therearcs to move rapidly across the surfaces ofthe between that moves upward because propelled. plateseither by theforce inherent in the arc itself or 40 -With these and other objects inview, the inby an additional blowoutfmagnet that may be 95 ventioncomprises the novel structurey and comprovided. The arc will be brokeninto a plurality bination and arrangement of parts that will be of shortarcs by the members of the arc-extinfully set forth in the followingdescription, taken guishing device 21, shown" in Fig. 1, and the inconjunction with the drawing, in which: clrcuitwill be established fromthe member 2 to Figure 1 iS a Side View, partly in section and a plate22 and thence, through the plurality of 100 partly in elevation, 0f aCircuit interrupter emshort arcs and U-shaped members 19,. to an endbodying my invention; p plate 26 and a flexible conductor 32 leading toFigS- 2 and 3 are, respectively, VieWS, in side the bolt 15. The seriesof short arcs just deelevation and in end or edge elevation, of onescribed will move rapidly in the spaces between of the U-shaped platesembodying a modified the members 19, as heretofore mentioned, and 105form of my invention. will thereby be deionized and quickly extin- Fig.4 is a fragmentary view, in side elevation, guished. 0f the assemblyShOWn in Fig. 2. It is clearly apparent to any one familiar with Figs. 5and 6 are schematic diagrams used in the contactor art that any othersuitable means explaining my invention. n for effecting engagement andseparation of con- 1N tact members might be employed, and, therefore, Ido not wish to limit the application of my invention to any particularcontactor.

Referring to Fig. 1 of the drawing, a plurality of U-shaped metal plates19 of the form shown in detail in Figs. 2 and 3 is assembled toconstitute the arc-quenching device 21, the lower ends of the U-shapedmembers 19 being posi-V tioned slightly above the contacts 2 and 5.

In the assembly of the elements of arc-extinguishing device 21, asupporting plate 22 is providedy with a lateral extension which may beattached to the terminal 2 by a bolt 23.

Insulating members 24 and 25 are employed to space the plates apart, thewidth of each space which has been found to be suitable for mostpurposes being one-sixteenth of an inch. By making the spaces betweenthe plates in which the arc plays very narrow, the ux is concentratedproviding a strong field along this whole length of the short arc tomove it rapidly without substantially bowing it out. By making thespaces in which the arcs play very narrow, a high reluctance path forthe ux is provided between the plates. Another method of making thereluctance of the flux paths between the legs of the U less than thereluctance in the arc spaces between the plates by the use of iron isdescribed below in connection with Fig. 3. For commercial-frequencyalternating-current circuits, a suicient number 0f U-shaped platesshould be assembled to provide one intervening gap for each 140 volts ofthe circuit to be interrupted.

When the required number of U-shaped members 19 have been assembled, anend plate 26 is spaced from the last U-shaped member by insulatingmembers 24 and 25, the entire assembly being clamped together by the.bolts 27 having insulating sleeves 28.

Between the legs of each U-shaped member 19, insulating members 29 areprovided to maintain the legs in their parallel relation when the bolts2'7 are tightened.

As shown in Fig. 1,' the insulating members 29 are of substantially thesame length as the legs of the U-shaped members 19 and, when soprovided, the'parallel legs of the members may be in closer proximity toeach other than other'- wise, as the insulation therebetween reduces thepossibility of arcing between the legs of the same member, therebyensuring that the path of the current will follow the U-shaped portionof the member.

The sides of the assembly 21 are enclosed by insulating plates31 thatextend below, and adjacent to, the sides of the movable contact 5 andthe terminal 2, thereby conning the arc within the width of thearc-extinguishing device 21. The plates 31 are provided with openingsthrough which the lugs 33 and 34 on' the end plates 26 and 22,respectively, extend in order to retain the plates on the sides of thestructure 21 as illustrated in Fig. 4. A flexible conductor 32 mayconnect end plate 26 to the bolt 15 through conductor 16.

The plates 19 of the device 21 may be made of non-magnetic conductingmaterial and, if so,

under many conditions, insure extinction of the arc. Under otherconditions, however, it is advisable to supply a magnetic means of oneform or another to assist in transferring the arc to the plates 19 andin moving itin the spaces provided therebetween.

For example, the desiredmagnetic eiect may simply and readily beobtained by forming the plates 19 from magnetic material. Alternatively,the insulating members 29, heretofore referred to, may be replaced by amagnetic member 30 that is covered with insulation 35 but is locatedbetween the legs in a position similar to that of the members 29 asshown in Fig. 3. In most cases, in which the iron is provided betweenthe legs of the plates or when the plates themselves are constructed ofmagnetic material, an additional arc-moving force, such as a separateblowout magnet, need not be provided, although it will be understoodthat the provision of such blowout magnets as are known in thecircuit-interrupter art is within the purview of my invention.

Enough details of thestructure embodying my invention having been setforth to enable its general characteristics to be understood, certainprinciples underlying its operation will now be explained.

If an arc deionizing and extinguishing device be made as shown in Fig. 6consisting of a plurality of fiat plates..35 in spaced relation to eachother, itis found that, under certain conditions, a portion only of thearcs, as at 36 and 37, are rapidly moved in the spaces interveningbetween the plates, the other arcs such as at 38 moving very slowly oreven remaining stationary. This is probably caused by the magneticeffects resulting from the ow of the current from one plate through the'arc and down through the adjacent plate to an adjoining arc. A simpleanalysis shows that current ow between arcs irregularly distributed overthe faces of successive plates sets up magnetic fields which drive thearc downward as indicated by arrow 39 if it is at the lower end of aplate, but tend to move the arc upward as indicated by the arrows 40 and41 if it is at the upper end of a plate due to the reaction between theVmagnetic ilux set up by the current flowing toward and away from thearcs as indicated by thearrows 42, and the current flowing in the arcs39, 40, and 41. This effect may be opposed by a suiiiciently strongimpressed magnetic field, but this impressed magnetic field needs to bemuch stronger than would be required if this loop effect did notvoccur.y

It is necessary to the successful operation of my arc deionizing deviceto have all the short arcs move with sufficient rapidity to prevent the'termini thereof, when passing over the surfaces of the plates, fromevolving metal vapors. In order to prevent such segregation of the arcsat the upper and lower ends of the plates and to obtain a similarmovement of the arcs in all of the spaces, I have substituted for thesimple fiat plates 35 just described, the plurality of U-shaped plates19 hereinbefore described. It can be shown that the magnetic effect ofcurrent iiow that conducts from each arc to the adjacent one through theU-shaped portion of ,the member is to cause the arcs to take up similarpositions in the different spaces since the current indicated by thearrows 43 flows upwardly to each arc 45, 46, and 47 and downwardly awayfrom each arc, irrespective of the position of the arc between theplates 19 and its relation to the other arcs. Thus, the magnetic eldsset up by the currents flowing in the U-shaped portion of metal betweensuccessive yshort arcs produce a driving force upon these.

arcs, moving them upward, as indicated by arrows 49, 50, and 51, in thespaces between the members with substantially equal forces and likespeeds ot movement.

As the speed at which the arcs are moved depends upon the extent; andmagnitude of the magnetic iield set up by the arc current and thespacing of the members 19, quantities should be taken into considerationwhen constructing arc interrupters of this type in order to make certainn that the legs of the U-shaped members 19 and the end plates 22 and 26are of such lengths that the arcs will have sufficient lengths ofsurfaces over which to travel without reaching the ends of plates 19during the half period of the alternatingcurrent cycle which may elapsebefore the line current passes through zero and then becomes k, extinct.

It will thus be seen that I have provided a deionizing device for an arcestablished by a circuit interrupter that moves the arc very rapidlyacross the cool surfaces of a plurality of metallic plates. The saidplates may, if desired, be of non-magnetic material, and they may haveassociated with them magnetic means for assisting in moving the arc. Theplates themselves may be constructed of magnetic material, thusstrengthening the iield about the current ilowing therethrough.

The plates are preferably made of U-shape in order that the' spacesprovided between adjacent members shall form similar current paths withthe arc, and that all of the arcs shall be acted upon in "the samemanner and with the same speed of movement. The number of plates, thewidths of the spaces and the lengths of the plates will all depend uponthe circuit in which my interrupting device is to be employed. Under allconditions, such dimensions should be so chosen that the speed of thearc movement shall always be great enough to prevent the arc fromburning the plates, under which condition, the arc will be deionized andextinguished within a half cycle of on the whole body of the short arcand drive it quickly upward so `that it does not burn the plates. -Dueto the fast driving action of the field, it is not necessary to providethe usual blowout coil required with the widely spacedplates of theprior art.

By closely spaced in the claims is meant such close spacing that themagnetic eld created by the current in the plates affects the whole bodyof the short arc.

. to be spaced more closely together.

It will be understood that, while I have de- The use of magneticmaterial for or between the plates has an additional advantage besidesstrengthening the magnetic eld acting on the arc. The lines of forceacting on thearc complete their circuit through the magnetic materialand hence do not travel into the space between adjacent plates toconflict with the lines of force acting on the adjacent arcs-Accordingly, the use of magnetic material prevents conflict betweenadjacent magnetic fields and permits the plates scribed the plates 19 asU-shaped, any other ari rangement in which current is forced tc pursuean outgoing and return path normal to the direction of current flow inthe arcs will be effective of the desired results. In general, allarrangements by which the current path between successive arcs is ofsuch form as to set up magnetic fields tending to produce axialalinement of successive arcs are Within the scope ofmy invention.

While I have shown and described but a single embodiment of myinvention, I do not wish to be limited to this particular structure, asmany changes, substitutions and omissions may be made from theembodiment illustrated, without departing from the spirit of myinvention. I desire, therefore, that the language of the appended claimsshall be construed broadly to cover all modifications and arrangementswithin the scope of my invention.

I claim as my invention:

1. The combination with a cuente-interrupting' device havingseparablecontact members, of a plurality of members of sheet materialfolded upon themselves in such manner that the folds are spaced fromeach other, insulating means spacing each said sheet member from anadjacent sheet member and a member of magnetic material between thefolds of each of said members.

2. In a circuit interrupter, means for causing an are, means forextinguishing said arc including a plurality of current conductingmembers yfolded upon themselves with the folds of each currentconducting member spaced apart, and each of said folded currentconducting members, being spaced from the adjacent current conductingmembers, and each of the folds of said currentconducting members havinga flux path therearound of lower reluctance between the folds of each,member than between adjacent members.

3. The combination with a circuit-interrupting device having separablecontact members, of arc extinguishing means comprising a plurality ofplates arranged in substantially parallel order, the end members of saidplates being connected to the circuit to be interrupted and the platesbetween said end members being electrically connected in pairs, and eachof said plates having flux 'paths therearound of low reluctance inthespaces between the plates forming each pair and of high reluctance inthe spaces between adjacent pairs.

4. The combination with a. circuit-interrupting device having separa-blecontact members, oi' arc extinguishing means comprising a plurality of125 plates` arranged in substantially parallel order, the end members ofsaid plates being connected to the circuit to be interrupted and theplates between said end members being electrically connected in pairsand a member of magnetic material between the plates forming each ofsaid pairs.

5. The combination with a circuit-interrupting device having separablecontact members, of arc extinguishing means comprising a plurality of 1plates arranged in substantially parallel order, the end members of saidplates being connected to the circuit to be interrupted and the platesbetween said end members being electrically connected in pairscloselyspaced together, a member of magnetic material between the platesforming each of said pairs, and a member of insulating material on eachside of said member of magnetic material insulating it from the platesadjacent thereto.

6. In a circuit interrupter, means for causing an arc, means forlextinguishing said arc includ-1 ing a. plurality of plates of goodconducting material positioned in spaced planes and electricallyconnected together in pairs at their edges adjacent said means forcausing the arc, said electrically connected pairs having open spacestherebetween -in which the arc is split up into short arcs and providingcontinuous U-shaped conducting paths of good conducting materialconnecting the ends of said short arcs, and said U- shaped conductingpaths having flux paths therearound of lower reluctance between the legsof the U than in the spaces between the plates in which the short arcsplay.

7. In a circuit interrupter, means for causingl an arc, means forextinguishing said arc including a plurality of plates of goodconducting material positioned in spaced planes and electricallyconnected together in pairs at their edges adjacent said means forcausing the arc, said electrically connected pairs having open spacestherebetween in which the are is split up into short arcs and providingcontinuous U-shaped conducting paths of good conducting materialconnecting the' ends of said short arcs, and a plate of magneticmaterial positioned betweenv the plates forming each of saidelectrically connected pairs, said magnetic plate being insulated fromat least one of the two plates between which it is positioned.

arcs, and the width of said open spaces between the electricallyconnected pairs in which the arc plays being of the order ofone-sixteenth of an inch.

JOSEPH SLEPIAN.

